Tuesday, December 21, 2010

Paul Thaggard's The Brain and the Meaning of Life

An Unpublishable Book Review: Paul Thaggard's The Brain and the Meaning of Life
I've recently read an interesting book by Paul Thaggard, "The Brain and the Meaning of Life". Since I'm a philosopher of mind and have taught about the meaning of life, it seemed a natural book to read. I thought it might be about how to make room in a physical world for meaning. However, it is not really that book. Instead, it is an attempt to construct a scientifically informed theory responding to great philosophical questions about freedom, morality, and meaning presented to a general audience. It feels unfair to criticize a general interest book for failing to come fully to terms with all the problems it raises. It is, in addition, a fairly reasonable account of how we can live in an ethical and meaningful way without belief in God, freedom or an immaterial soul. I do not have substantive criticisms of his arguments for the value of science, the denial of the existence of God and the soul, or (mostly) his views on free will. That said, I have serious reservations about the book.

First, however, I'll describe Thaggard's book a little more.

The work is an anti-philosophical work of philosophy. Thaggard works in the tradition of C.S. Peirce, who argued that the metaphysical intuitions of his contemporaries were just disguised prejudices of their culture, no better than an appeal to popularity. Thaggard is particularly skeptical of the thought experiments one often finds in the professional literature, especially on topics such as personal identity or free will and determinism. I think there is reason to be skeptical of our intuitions, but it's also not clear what else we have to go on for claims about morality and meaning.

Indeed, given Thaggard's distrust of philosophical and a priori intuitions, it's not clear how he can justify the arguments in his own work. His goal is to rely only on empirical evidence, but it's not obvious how empirical evidence is to apply to most or all of his questions. For example, Thaggard relies on surveys of subjective well-being to argue that money (beyond a certain minimum) is not necessary for a meaningful life. The features he does find in the literature are rewarding work, love and play, which appeal to basic human needs. It's not entirely clear what makes these qualify as needs since one can survive without at least some of them. He relies on an account of human needs found in the literature on psychology, but classification of these goods as needs does not have any empirical justification (at least, I don't recall him giving any.)

On the other hand, Thaggard argues that having children contributes to the meaning of life. Yet, it turns out that having children does not contribute to subjective judgments of one's own happiness or well-being. Thus, when it comes to the value of children for the meaning of life, we must abandon the empirical evidence that links meaning to subjective judgments of well-being. I suspect most will agree with Thaggard that happiness (understood subjectively) is not the same as meaning. We may even agree that children do contribute to the meaning of life despite the lack of an effect on subjective judgments of happiness. The difficulty, however, is that Thaggard offers no concrete evidence to take children to be an exception to the empirical evidence he uses in his other claims about meaning. Thaggard, instead, appears to rely on our popular intuitions about meaning. This appears to be exactly the kind of intuitive, a priori reasoning that Thaggard pretends to reject.

Thaggard must realize that one cannot draw normative conclusions (about the meaning of life and morality of actions) from descriptive phenomena (such as subjective judgments of happiness), but he offers nothing in the way of a method to replace the one that he claims to reject and indeed appears to rely on that very method himself. I would be much happier with a book that offered some reason to accept these intuitive judgments about normativity even if they might be less reliable than conclusions drawn from scientific evidence.

Thaggard's rejection of a priori intuitions and reasoning is, in fact, much stronger than one finds in even most hardened empiricists. He rejects claims that mathematics and logic can provide any true knowledge. At least Thaggard considers the case and gives reasons to deny that even mathematics can give real knowledge of something beyond our own minds. Thaggard's reason to reject a priori knowledge of even mathematics is that some people (in particular, postmodernists) have rejected even the most apparently simple and undeniable a priori claims such as the law of non-contradiction. If, he says, people can believe that two logically contradictory claims can both be true, then there is literally nothing that everyone accepts as logically and necessarily true. Thus, there are no universal, a priori, logical truths.

This is peculiar reasoning. First, relying on what postmodernists say about their beliefs is unreliable. Jacques Derrida, for example, may claim that the law of non-contradiction is not true, but that may be (and probably is) just for the fame that comes from denying something that everyone knows to be true. There are significant social rewards for contrarianism, and it's more likely that he's saying something that he doesn't believe than that he really believes.

Nonetheless, people may believe all manner of crazy things, so it's possible that some people really do reject the law of non-contradiction (just as many have attempted to believe in the holy trinity). The problem with Thaggard's reasoning is that he demands that everyone believe something in order for it to count as a priori knowable. He even comments that we can learn about mathematics by studying human psychology. But these are just outright wrong-headed claims. This is simple psychologism. Mathematics and logic are not about what people believe. More people accept affirming the consequent as valid than accept modus tollens. Should we revise our logic texts to reflect that? In fact, I doubt more than a single percent of the population as a whole could understand, let alone properly apply, the inference patterns of a standard symbolic logic text. But we should not delete them from the curriculum, or take them to involve invalid reasoning, for that. The point is that when these rules of inference or logical claims are properly understood, using truth tables, for example, to show why they are in fact valid or invalid, then their validity or truth is undeniable by a rational being. Yes, my reasoning is shot through with assumptions about normativity and abstraction, but the alternative is nothing short of absurd.

Consider the possibility that logic is about what people believe. For one thing, since people sometimes believe contradictory things, we have no reason to reject contradictions as false. How, then, are we ever to prove anything if, despite our most cogent proof, it is still perfectly acceptable to deny the claim that we have just accepted?

If a priori truths are determined by what everyone believes, then if everyone believes that a priori truths are not determined by what everyone believes, then they are not in fact determined by what everyone believes. (Thaggard may have the out that he at least does believe they are based on psychology, and anyway, the fact that his claim is contradictory is not great problem.) If this is Thaggard's standard, then his entire work is a waste of time since people could perfectly reasonably accept the empirical evidence for his conclusions and at the same time believe the exact opposite since there is no objective logic proving that this is an invalid inference. (In fact, that's how many ordinary readers might respond to his work: "I don't see what's wrong with his reasoning, but I reject it anyway." One hopes that Thaggard would not find this an adequate reason to reject his work. So, why accept a theory of a priori knowledge that allows for it?)

Am I being unfair to Thaggard? Maybe. He does claim that mathematics is a kind of fictional discourse, and one can make true or false claims about fiction even if nothing in reality corresponds to them. Does fictionalizing mathematics resolve these problems? I don't think so. For one thing, we have no clear understanding of how truth works in fiction. You cannot explain how mathematics can be true by relying on another field in which truths are not understood. You cannot solve a mystery (truth of claims in mathematics) with another mystery (truth claims in fiction).

But suppose we understood fictional discourse. That still would not resolve the problem. Fiction is essentially arbitrary. The color of Harry Potter's eyes is chosen by J.K.Rowling; there is no reason or justification for her choices, and there need not be one. I'm sure that Thaggard would say that the basic laws of logic, valid inference patterns etc. could not be justified either and so would be equally arbitrary. It is, in fact, hard to see what justification one can offer for modus ponens (besides looking at the truth table which, no doubt, are a lot less obvious than is modus ponens itself and, indeed, might even rely on it to be understood). Nonetheless, it logically follows that if Harry Potter's eyes are entirely blue all over all the time, then they cannot also be entirely brown all over all the time. Why does this follow? Is this also an arbitrary choice made by Rowling? No, she probably would never have thought any such thing. They are not brown because making them blue entails that they are not brown. Similarly, she did not also have to think that they are not green, not red and not tuning forks. Logic still must hold for fiction; logic is a basic underpinning of the truths in fiction and cannot be just another arbitrary system on a par with it.

The self-refutation argument is probably the best way to see this. If logic is just an arbitrary system, determined by a set of people, call it the "math/logic community", which defines those rules, then suppose the community believed that those rules were universally applicable with a force beyond simple psychology. (They need not actually have said this; it must just be possible.) Then, if mathematical/logical statements are true just in case they are accepted by the community, then mathematical/logical statements are true universally, not just for those in the linguistic community. If they are true, they must be universally true.

In reply, surely, one must say that these are no universal a priori, logical truths, only truths relative to a community. But what is the justification for this? Is this true because it has been accepted in a community? (Actually, relativism has rarely been accepted by any group.) Or is it universally true, applying even to the logicians who reject it? If so, then Thaggard has contradicted himself, claiming there are no universal, a priori truths, while offering a universal a priori truth (and if this claim is a posteriori, I'd love to know what his evidence is). If not, then the universalist's claim takes precedence over the relativist's claim. The relativist says: there are only relative truths. Realist says: Realism is universally true for me, and therefore it is universally true and so true for you as well.

These major reservations aside about his problems with having a consistent method for his reasoning and his absurd rejection of all a priori knowledge, Thaggard does have some reasonable thoughts to offer about morality and meaning. Some of it misses the point (he talks about how moral sensibility develops in humans when he raises the question of what justifies moral claims or justifies us in being moral), and he does not properly justify his theory of meaning (given his rejection but continued use of a priori reasoning). Still, general readers would come away with a better way of thinking about themselves, their lives and how to live them than they would have if they continued in their traditional religious beliefs.

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